In the words of Matter et al. (2013), "gene flow connects populations, maintains genetic diversity, prevents inbreeding and facilitates the spread of adaptive genes across a species range," citing Slatkin (1985, 1987) and Ellstrand and Elam (1993). And, therefore, they state that "understanding how plant populations are connected by gene flow, particularly across altitudinal gradients in mountain regions, will improve our understanding of how they will respond to future environmental change." In an attempt to gain some of that important "understanding," the four Swiss scientists studied patterns of historic gene flow, flowering phenology and contemporary pollen flow in two common herbs (Ranunculus bulbosus and Trifolium montanum) along an altitudinal gradient of 1200-1800 meters a.s.l. over a distance of 1 km among five alpine meadows in Switzerland.

From their analysis, Matter et al. discovered that "historic gene flow was extensive," with their data suggesting that "contemporary pollen flow is not limited across altitudes in either species." Given such, the authors final conclusion was that "high levels of pollen flow among altitudes in both R. bulbosus and T. montanum should facilitate exchange of genes which may enhance adaptive responses to rapid climate change."

Additional References
Ellstrand, N.C. and Elam, D.R. 1993. Population genetic consequences of small population size: implications for plant conservation. Annual Review of Ecology and Systematics24: 217-242.